Performance And Microbial Community Structure Of Phosphorus Removal Sludge With Different Electron Acceptors

Denitrifying phosphorus removal becomes the hot research topic due to theadvantage of simultaneous nitrogen and phosphorus removal, saving of carbon sourceand low sludge production. Great advances had been carried out on the parameters onoperation performance. In the current study, phosphorus removal performace andmicrobial community structure with three different carbon sources were studied for thefurther understanding of denitrifying phosphorus removal processes as well as microbialcommunity structure, and then to perfect the denitrifying phosphorus removal.Three biological phosphorus removal systems (RNO3, RNO2, RO2), seeded with thesludge from the secondary settling tank of the A2/O process, were established withnitrate, nitrite and oxygen as the sole electron acceptor. It was fastest for the RO2toachieve successful acclimation, followed by RNO3and RNO2. Phosphorus removal rateswere averaged at82.7%,73.5%and86.7%, respectively, and the phosphorus uptakerates were9.43,8.68,10.8mgP/(gVSS h). Moreover, nitrification rates were9.59and10.4mgN/(gVSS h)for RNO3and RNO2respectively. The effect of heavy metals onphosphorus removal processes was investigated. The inhibition of heavy metalas onanaerobic phase was less than anoxic and aerobic phases, and the influence of Cr6+wasmuch more obvious than Cu2+. In addition, the inhibition on RO2was more obvious thanthe other two systems under higher concentrations (10,20mg/L) of heavy metals.The community structure of three biological phosphorus removal sludge sampleswere studied based on PCR and high-throughput sequencing of16S rDNA. Resultsshowed that RNO3sludge had the highest diversity, followed by RNO2and RO2sludge.RNO3and RNO2sludge under anaerobic-anoxic conditions had similar communitystructure. Proteobacteria was dominated on the Phylum level for all sludge.-Proteobacteria (23.0%~33.8%) was the dominant group on class level, followed by-(9.12%~34.9%),-(3.73%~10.4%),-(0.39%~5.22%). Proportions of phosphorusaccumulating organisms in three systems were1.78%,2.54%,4.81%, and proportionsof glycogen accumulating organisms were1.44%,1.32%,31.0%, respectively.Anaerobic/anoxic condition was favorable for suppressing glycogen accumulatingorganisms significantly.The effect of post-aeration on deinitrifying phosphorus removal was investigated.With the post-aeration time changed from0min to30min, the sludge settlingperformance was improved, but the denitrifying phosphorus removal performance wasdeteriorated. Moreover, post-aeration time also affect the microbial community structure.Based on the result obtained in the current study,10min of post-aeration was proposedfor denitrifying phosphorus removal process.